1. Field of the Invention
The present invention relates to a vacuum processing apparatus, and more particularly to a vacuum processing apparatus suitable for processing such as the etching of a semiconductor wafer or film formation.
2. Description of the Related Art
In a dry etching technique to be used as a microprocessing method for a semiconductor integrated circuit (LSI), a high precision of a 0.1.mu.m level is required in response to an increase in fineness of LSI. Further, high-speed processing is also required with a microprocessing level of 0.8.mu.m, 0.5.mu.m or 0.3.mu.m, while it is also required to reduce a cost of such a dry etching apparatus. However, in a dry etching apparatus as described in Japanese Patent Laid-open Publication No. 6437021, a vacuum processing chamber is not connected directly to an exhaust pump or an exhaust conductance adjusting function.
In the prior art mentioned above, a shortening of an exhaust path is not taken into consideration. That is, a reduction in substantial exhaust conductance is brought about. Accordingly, a large-power or costly exhaust pump is selected, so as to obtain an intended ultimate vacuum in the vacuum processing chamber. In such a large-power exhaust pump, however, a flange diameter of the exhaust pump is large to cause an increase in center distance between the vacuum processing chamber and the exhaust pump, that is, an increase in length of the exhaust path, resulting in a reduction in exhaust conductance. Further, an actual exhaust speed of the exhaust pump is small in the process, so that a selectable range of a processing gas flow is narrow to hinder an improvement in performance. For example, as in an ECR etching device described in "Solid State Devices and Materials", P 207, 1990, etching of polysilicon is performed with Cl.sub.2 flow rate of 20 sccm under a low gas pressure of 0.5 mTorr. In this etching, an etching speed of the polysilicon is not greater than 300 nm/min. Further, in etching of Si or SiO.sub.2 to form a deep groove such as a trench or a contact hole, an etching speed under such a low gas pressure is too small. Thus, in the prior art etching, it is difficult to obtain a high etching speed under a low gas pressure of 0.5 mTorr or less.